Abstract

The immune response in a patient with acute babesiosis was determined by measurements of lymphocyte subpopulations, serum levels of cytokines, and adhesion molecules. The ratio of CD4+:CD8+ lymphocytes was reduced early in the infection, but returned to a normal value after treatment with azithromycin and quinine. Natural killer (NK) cells markedly increased in the acute phase but progressively decreased and to the normal range in the convalescent phase. Serum levels of tumor necrosis factor-alpha, interferon-gamma, interleukin-2 (IL-2), IL-6, E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 were highly elevated in the acute phase while normal levels of these mediators were observed one month after treatment. These results suggest that CD8+ T cells and NK cells may be involved in the host defense mechanisms against acute babesiosis.